Make the chimichurri: add olive oil, red wine vinegar, parsley, garlic, chili flakes, oregano, and salt and pepper to taste in a small bowl. Stir to combine. Let the sauce rest for 10 minutes before serving or ideally for 2 hours.
Make the steak:
Cook the steak: season the steak with salt and pepper to taste. Heat a cast iron skillet with a splash of olive oil.
Cook the steak for 5 minutes per side or until it reaches the desired doneness. Transfer the steak to a cutting board and let it rest for 5 minutes before slicing.
Serve:
Slice the steak and serve with chimichurri.
Notes
Adjust the chimichurri to taste your tastebuds by adding more or less chili flakes, salt, and pepper.